python,使用枚举类，面向对象高级编程

python

#针对常量
#枚举类型定义一个class类型，然后，每个常量都是class的一个唯一实例。

from enum import Enum

Month = Enum('Month', ('Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'))
#这样我们就获得了Month类型的枚举类

for name, member in Month.__members__.items():
    print(name, '=>', member, ',', member.value)
#value属性则是自动赋给成员的int常量，默认从1开始计数。

如果需要更精确地控制枚举类型，可以从Enum派生出自定义类：

from enum import Enum, unique

@unique
class Weekday(Enum):
    Sun = 0 # Sun的value被设定为0
    Mon = 1
    Tue = 2
    Wed = 3
    Thu = 4
    Fri = 5
    Sat = 6
#@unique装饰器可以帮助我们检查保证没有重复值。

#访问这些枚举类型可以有若干种方法：

day1 = Weekday.Mon
print(day1)Weekday.Mon
print(Weekday['Tue'])   Weekday.Tue
print(Weekday.Tue.value)  2
print(Weekday(1))   Weekday.Mon
print(day1 == Weekday(1))True

for name, member in Weekday.__members__.items():
    print(name, '=>', member)
#结果
Sun => Weekday.Sun
Mon => Weekday.Mon
Tue => Weekday.Tue
Wed => Weekday.Wed
Thu => Weekday.Thu
Fri => Weekday.Fri
Sat => Weekday.Sat